Guru Nanak Sahib prepared Deer Meat at Kurukshetra - Giani Gian Singh

Acc to many historical resources including Giani Gian Singh, mentioned Guru Nanak Sahib cooking Deer meat to break illusion of people. There is also a gurdwara marked remembrance of same event

Gurdwara Sidh Vati Sahib where Deer meat was prepared

Meat at Langar During Guru Angad Dev Ji times - Sri Gur Partap Suraj Granth

In Gur Partap Suraj Granth, Kavi Santokh Singh ji mentioned that during Guru Angad Dev Ji's times meat Langar was part of Guru ghar

ਪੰਕਤਿ ਬੈਠੀ ਮੀਲਿ ਤਬਹਿ ਗੁਰ ਬੀਚ ਸੁਹਾਏ 

ਮਿਲਿ ਸੰਗਤੀ ਮਹਿਂ  ਅਮਰ ਜੀ ਬੈਠੇ ਤਿਸ ਥਾਏ 

ਪਹਿਤ ਭਾਟ ਬ੍ਰ੍ਤ੍ਯੋ ਪਰਥ, ਪੁਨ ਆਮਿਖ ਆਵਾ

ਇਕ ਦਿਸ਼ ਪੰਕਤਿ ਮਹਿਂ ਦਯੋ ਤਬ ਇਨ ਦਰਸਾਵਾ  

( ਆਮਿਖ - Mahaparshaad)

Giani Gian Singh ji also quoted the same in Twarikh Guru Khalsa.

Guru Gobind Singh Killed a Bull to remove Hunger of Dev

GURUDWARA SHRI QILLA MUBARAK SAHIB is situated in the Distt City Bathinda. It is situated inside old Bhathinda Fort, hence the name is Qilla Mubarak Sahib. GURU SAHIB came to Bhathinda via Bhagu. GURU SAHIB met Haazi Ratan, and had discussion with him. GURU SAHIB also set him free from Cycle of Life and Death. When People of Bathinda came to know about GURU SAHIB's visit, They, in large number came for GURU SAHIB's darshan. Further they requested GURU SAHIB to come to Qilla (Fort). Accepting there request GURU SAHIB accompanied them to Qilla. GURU SAHIB came here and asked people that if they have any problem in life. People requested GURU SAHIB that theres a monster ( Deo ) who distroys theres houses and disturbs them. Kindly get them free from from monster. GURU SAHIB called upon monster and asked him that why was he disturbung people. He bowed in front of GURU SAHIB and told that he was hungry from long time. Kindly do some thing for him, he will leave the fort for ever. GURU SAHIB sat for some time and found that there was Bull common of ten villages. People were also disturbed from that Bull. GURU SAHIB send some Singhs to get that Bullock. When Singhs reached village Nat Banger they asked people about that bull. People laughingly told that bull was sitting in water. Bhai Mailagar Singh went to him and asked " Chalo Bhai GURU SAHIB ne Bulayaa hai" Bull came out and Singhs started following him towards Bhathinda. Bull reached Fort in front of GURU SAHIB. GURU SAHIB asked Bhai Mailagar Singh to cut Bull's head in one attempt of sword. Bhai Sahib did the same way. And it was offered to monster and his hunger was fullfilled. GURU SAHIB sent monster to sirhind and told him that his services will be needed there.

The Monster is now days around Sirhind

Historical Gurdwaras Link

Guru Har Rai also go for Hunting expedition - Mahima Parkash

In Sakhi 4, Mahima Parkash covers this fact that Guru Har Rai j. Same source also suggests that Guru Har Rai ji was Vegetarian by Diet and also stopped cooking Animal Food in Langar, i.e till first 6 Gurus Animal Food was part of Langar Sahib. After this Guru Gobind Singh and Khalsa is shown as taking Animal Food as diet. Though he is shown as animal lover but he go for Hunting Practice also.

ਸੁਨ ਮੁਸਕਰਾਏ ਸਤਿਗੁਰ ਮਗ ਲੀਆ
ਕਾਹੂ ਕਛੁ ਉਤਰ ਨਹੀ ਦੀਆ
ਖੇਲ ਸਿਕਾਰ ਗ੍ਰਿਹ ਮੋ ਪੁਨ ਆਏ
ਆੰਦ ਮੰਗਲ ਹਰੀ ਕੇ ਗੁਣ ਗਾਏ !੧੩!
ਪੁਨ ਮਿਲ ਸਭ ਸੰਗਤ ਕੀਆ ਬੀਚਾਰ
ਗੁਰ ਛੂਧਾ ਵੰਤ(ਭੁਖ) ਹੋਈ ਸਮੇ ਸਿਕਾਰ | 
ਜਬ ਅਗਲੇ ਦਿਨ ਸਿਕਾਰ ਗੁਰ ਗਏ|
ਕੇ ਸਿਖ ਪਰਸਾਦੀ ਮਗ ਠਾਡੇ  ਭਏ |੧4|
ਸਾਖੀ ੪, ਪਾਤਸ਼ਾਹੀ ੯ 

Singhs play Shikaar at Anandpur Sahib - Mahima Parkash

At Anandpur Guru Sahib got complaint that Singhs play Hunting at fields of kings and this ruin their Fields:


.....ਏਤੇ ਮੋ ਰਾਜਿਆ ਕੇ ਵਕੀਲ ਆਏ | ਅਉ ਬੇਨਤੀ ਕੀਆ | ਜੋ ਹਜੂਰ ਕੇ ਸਿੰਘ ਹਮਾਰੇ ਖੇਤਾ ਮੈ ਸਿਕਾਰ ਖੇਲਤੇ ਫਿਰਤੇ ਹੈਂ | ਵਾ ਨਾਹਕ ਭੀ ਘੋੜੇ ਖੇਤਾ ਮੈ ਲੈ ਜਾਤੇ ਹੈ | ਹਮਾਰਾ ਹਜ਼ਾਰਾਂ ਰੁਪਿਆ ਕਾ ਨੁਕਸਾਨ ਹੋਤਾ ਹੈ |.....
Sakhi 22, Mahima Parkash

Guru Gobind Singh ate Goat Meat at Machiwaadaa - Mahima Parkash

In Sakhi 23, It is mentioned that when Guru Gobind Singh reached Machiwarha where he did Jhatka of Goat and took dinner of it.

The text is:
....ਸਾਮ ਤਕ ਮਾਛੀਵਾੜੇ ਆਏ ਪਹੁਚੇ | ਰਾਤੀ ਕੋ ਉਹ ਬ੍ਰ੍ਹਮਨੀ ਕੇ ਘਰ ਉਤਰੇ | ਰਾਤ ਕੋ ਬਕਰਾ ਮੰਗਾਈ ਕੈ ਝਟਕਾ ਕਰਵਾਇਆ | ਪ੍ਰਸਾਦ ਛਕਾ ਅਰ ਛਿੰਗਾ ਉਸ ਕਿਆ ਪਿਛਵਾੜੇ ਮੁਸਲਮਾਨਾ ਕਾ ਘਰ ਥਾ ਊਹਾ ਫ਼ੇਕੀ |....

Akal Takhat Rehat Maryada allows to eat Jhatka Meat

In Section 6 of Akal Takhat Rehat Maryada, it is written as,

Ceremony of Baptism or Initiation

Article XXIV Sub-section p:

The undermentioned four transgressions (tabooed practices) must be avoided

• Dishonouring the hair;
• Eating the meat of an animal slaughtered the Muslim way (Ritual Killing)
• Cohabiting with a person other than one's spouse;
• Using tobacco.

Link

This clearly states that Sikhs have no Ban on taking Jhatka Meat.